1. Field of the Invention
This invention relates to a remote control commander for an electronic appliance, such as a television set, and more particularly to an optical motion sensing remote control system for an electronic appliance.
2. Related Art
An IR (Ifra Red) remote commander is a common means to control a TV from a distance. However, existing remote commanders have some drawbacks. They are easy to lose. The user often mistakes a VCR commander for the TV commander. In fact, a lot of people have a great xe2x80x9cremote commander collectionxe2x80x9d. Also one has to learn which button is where on the commander. Remote commanders require batteries which have to be replaced periodically. If a TV could have a camera vision and read the user""s gestures, no remote commander would be necessary. However, it is not easy for a TV to distinguish gestures from other moves in its camera view. One would not want the channel to change each time the user got up to fetch a snack from the kitchen, for example.
The above and other problems of prior art electronic appliance remote controllers are overcome by an electronic appliance remote controller according to the present invention which includes a display screen (which may be part of the appliance, e.g. a TV screen) for displaying icons representing possible operations of the electronic appliance, and a motion detector circuit for detecting a motion within a field of view of the motion detector circuit. The motion detector circuit detects either the image of the user""s hand or a predetermined motion of the user""s moving hand within the field of view as an indication that a remote control operation is to be started and, thereafter, tracks the movement of the hand. The motion detector circuit outputs a cursor control signal representative of the motion of the hand. A control circuit, connected to the display screen, the electronic appliance, and the motion detector circuit and supplied with the cursor control signal, controls the display screen to display a movable visual indicator, e.g. a cursor, whose own motion tracks the movement of the moving hand. The control circuit also controls the electronic appliance to perform operations corresponding to the icons selected by the user using the visual indicator.
In a preferred embodiment, the motion detector circuit detects the selection of an icon by the user by detecting a predetermined motion pattern of the hand when the visual indicator is coincident on the display screen with a particular icon. For example, the motion detector circuit detects the selection of an icon by the user by detecting a cessation of movement of the hand for a predetermined period of time after the visual indicator is coincident on the display screen with a particular icon. Alternatively, the motion detector may detect a hand movement akin to pushing in the icon as one would push in a button.
In the preferred embodiment, the motion detector circuit includes at least one video camera, random access memory interface, a random access memory, and a CPU and detects motion by comparing corresponding pixel values in each macro block of two successive video frames output by the camera. If the absolute value of the differences for two corresponding macro blocks from the two successive frames exceeds a predetermined minimum value, it is judged that motion has taken place in that macro block and it is an active region.
In one embodiment, for each video frame, the motion detector circuit, in determining whether to track a hand, checks to determine if a detected active region satisfies the conditions (a) that the active region made one linear movement in a first direction and (b) the active region returned to the start position where it used to be. The motion detector locks onto that region if conditions (a) and (b) are both satisfied. Naturally, any sort of repetitive movement could be used to cue the motion detector to lock onto the hand motion.
In another embodiment, the motion detector compares a user selected portion of the video image output by the camera with a stored video image and determines that the user selected portion of the video image output by the camera is the user""s hand if there is a match with the stored video image. Various means are provided for allowing the user to select the portion of the video image as his or her hand.
In order that the same general length of hand movement will control the visual indicator to move a consistent corresponding length of movement, the control circuit includes an automatic cursor sensitivity adjustment feature which automatically scales the extremes of the movement of the visual indicator to the extremes of the predetermined hand motion so that, for example, the same diagonal motion of the user""s hand will cause the visual indicator to move just across the diagonal of the display screen regardless of whether the user is close to the motion detector circuit or far away.
A remote control method for an electronic appliance according to the invention begins with the step of detecting the user""s hand either by (a) recognizing a portion of an image in a video camera""s output as the user""s hand or (b) recognizing a first predetermined hand motion within a field of view. Recognition of the user""s hand is an indication that a remote control operation is to be started. The next step is visually displaying on a display screen, such as a TV screen, icons representing possible operations of the electronic appliance (e.g. a TV). Thereafter, remote control is carried out by tracking the movement of the hand and outputting a cursor control signal representative of the motion of the hand. Responsive to the control signal, the display screen is controlled to display a movable visual indicator, e.g. a cursor, whose movement tracks the movement of the moving hand. The electronic appliance is then controlled to perform operations corresponding to the icons selected by the user using the visual indicator. The first predetermined motion can be any hand movement, such as a back and forth hand movement, for example.
The step of detecting the selection of an icon by the user includes detecting a second predetermined motion pattern of the hand when the visual indicator is coincident on the display screen with a particular icon. For example, the predetermined motion pattern could be a cessation of movement of the hand for a predetermined period of time after the visual indicator is coincident on the display screen with the particular icon or, by the use of two orthogonally placed cameras, detecting movement of the user""s hand which emulates pushing in an icon as one would push in a button.
The motion detecting step uses at least one video camera in the preferred embodiment and includes comparing corresponding pixel values in each macro block of two successive frames. If the absolute value of the differences for two corresponding macro blocks from the two successive frames exceeds a predetermined minimum value, it is judged that motion has taken place in that macro block and it is an active region. For each frame, in determining whether to track a hand, a check is made to determine if a detected active region satisfies the conditions (a) that the active region made one linear movement in a first direction and (b) the active region returned to the start position where it used to be. That region is locked onto if conditions (a) and (b) are both satisfied. Naturally, any sort of repetitive movement could be used to cue the motion detector to lock onto the hand motion. If two video cameras are used, this process is run in parallel for the outputs of both cameras.
In order that the same general length of hand movement will control the visual indicator to move a consistent corresponding length of movement, the remote controlling method according to the invention further includes a step of automatically adjusting the sensitivity of the visual indicator by the steps of automatically scaling the extremes of the movement of the visual indicator to the extremes of the predetermined hand motion so that, for example, the same diagonal motion of the user""s hand will cause the visual indicator to move just across the diagonal of the display screen regardless of whether the user is close to the motion detector circuit or far away.
The foregoing and other objectives, features and advantages of the invention will be more readily understood upon consideration of the following detailed description of certain preferred embodiments of the invention, taken in conjunction with the accompanying drawings.